The invention pertains to a circulating fluidized bed reactor.
Such fluidized bed reactors are used in power engineering and power plant engineering, among other applications. There, coal or other combustible materials, such as trash or biomass, for example, are burned in the fluidized bed of the reactor combustion chamber. In order to separate and recirculate a portion of the solid particles contained in the flue gas back into the reactor chamber, the fluidized bed reactor exhibits a centrifugal separator, generally a cyclone separator. In conjunction with this, the separated solid particles are fluidized prior to their recirculation into the combustion chamber, and are conveyed to the combustion chamber inlet openings in order to be distributed essentially uniformly over the width of the fluidized bed.
Such a fluidized bed reactor has become known from specification EP 0 161 970 B1. The technical teaching of this document provides that separated solids are drawn from the cyclone separator by means of a vertical standpipe. At its lower end, the standpipe leads to the center of a duct that is placed horizontally and parallel to the back wall of the combustion chamber, and from each of the two ends of the horizontal duct, a pipe leads first vertically upward and then inclined diagonally downward into the combustion chamber. In order to distribute the solid material within the horizontal duct and continue the conveyance, a fluidizing device, which exhibits multiple air chambers and through which a fluidizing gas, usually air, is supplied, is provided inside the horizontal duct.
In this known arrangement of the recirculation of solids into the combustion chamber, it proves to be disadvantageous that, due to the protruding horizontal duct underneath the standpipe, there is a large space requirement in the area of this duct and as a result, the design cannot be executed in a compact fashion. This has a negative effect on the placing of the surrounding components such as the coaling conveyers, for example, which have to be placed at a greater distance from the coal discharge into the recirculation pipes. In addition, markedly more fluidizing air is needed for the fluidization of this horizontal duct than is the case in facilities that have only a recirculation pipe and thus no horizontal duct.